1. Field of the Invention
The present invention relates to a polyester resin composition. More particularly, the present invention relates to a polyester resin composition reinforced with inorganic fibers and having an improved mold release property.
2. Description of the Prior Art
It is well known that polyester resins, especially polyethylene terephthalate resins, exhibit very superior chemical and physical properties and thus are highly useful as various fibers, films, and engineering plastics. Utilization of the polyester resins as engineering plastics has recently been increasing and is expected to increase even further in the future.
In the production of engineering plastic articles from a polyester resin composition by means of a molding process, it is important to increase the mold release property of the molded article so as to minimize the molding cycle time. For this purpose, a specific agent for increasing the mold release property is usually added to the polyester resin composition.
There are many different mold release agents in practical use. However, conventional mold release agents are sometimes disadvantageous. For example, some conventional mold release agents highly effective for improving the mold release property of a polyester resin composition decrease the mechanical strength of the molded article or discolor the molded article by gases generated therefrom.
Other conventional mold release agents, which do not degrade the mechanical strength and appearance of the molded article, do not satisfactorily improve the mold release property of the polyester resin composition and sometimes cause undesirable irregular noise (creaky noise) during the molding procedure.
Under the above-mentioned circumstances, it is strongly desired, especially in the field of high cycle molding resin compositions, to provide a new type of polyester resin composition free from the above-mentioned disadvantages.